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Carvin PB300C - EXT system?

MattS

MattS

Jan 17, 2011
267
115
Cheshire, CT
#1
Greetings!
I have this Carvin PB300C 15" bass combo amp that I absolutely love! But I'm considering running a second speaker with this, but I'm having a hard time understanding the "EXT system" on the cabinet control plate. Can anyone shed some info on how to use this and what is the difference between using the SPKR 2 from the head to a second speaker cab vs. whatever the function of the EXT SYSTEM is? What options do I have?

The manual doesn't really say much for the EXT SYSTEM jack, but it does say
"You may plug any 2ohm, 4ohm, or 8ohm speaker into the two speaker output jacks. The maximum capacity is four 8ohm speakers Y into the two jacks for 2ohm or from one jack for a total minimum impedance of 2ohm. By adding an additional power amp, you may use the electronic crossover for bi-amping"

8ohms 150watts
4ohms 200watts
2ohms 300watts

IMG_6534.jpg

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Thank you,

Matt
 
#3
It's an older amp so I would just add another 8 ohm 15" cab and call it a day. Not saying it won't run safely at 2 ohms, because it's designed to do so, but it's more likely to have a problem at 2 ohms than 4 ohms. If you add a 4 ohm cab, that cab will get more power and it won't be "even" with the combo's internal speaker.
I had a PB-100 and it was my rehearsal amp with a loud rock band for like 3-4 years, once a week for like 2-3 hours. It was a champ.
 
#4
jeff7bass said:
It's an older amp so I would just add another 8 ohm 15" cab and call it a day. Not saying it won't run safely at 2 ohms, because it's designed to do so, but it's more likely to have a problem at 2 ohms than 4 ohms. If you add a 4 ohm cab, that cab will get more power and it won't be "even" with the combo's internal speaker.
I had a PB-100 and it was my rehearsal amp with a loud rock band for like 3-4 years, once a week for like 2-3 hours. It was a champ.
Click to expand...

this is what I’m thinking aiming to do; adding an 8ohm 15” or 12” or 2x10” cab, but what is the “EXT SYSTEM” and how is that used?
 
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#7
That's an interesting, odd beast.
The manual states that SPKR1 and SPKR2 are internally connected in parallel, so there is no difference between connecting one cabinet to each output vs chaining additional cabinets from one output. As Carvin states that the amp is 2 oms stable, this provides for a lot of flexibility for attaching speakers.
The combo's speaker is a PS15C-8, rated at 8 ohms. I'm assuming you'd continue to use it, and aren't interested in bi-amping, which would require an additional power amplifier for the low frequencies. As the speaker input plate of this combo also has a parallel output for another cabinet (labeled EXT System), it would be easy to add another 8 ohms cabinet to that as well.

SPKR1 SPKR2 Total Load
8 ohms 8 ohms 4.00 ohms --> Good!
8 ohms 4 ohms 2.67 ohms --> Good!
4 ohms 8 ohms 2.67 ohms --> Good!
4 ohms 4 ohms 2.00 ohms --> Good!

The 4 ohms in the example could be a single 4 ohms cabinet or two 8 ohms cabinets together.

Man, I wish there was an easy way to make tables in these messages!
 
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#9
I have the same combo as well as another PB300C that doesn't have the XLR speaker connectors, as mentioned above it's just another speaker connection. I've run mine down to 2 ohms no problem, the manual states if you run into problems at 2 ohms to engage the crossover switch and set the cross over to 40hz this will roll off some ultra lows and save power. I replaced the XLR speaker connection with Speakon.
 

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